Arthrochilus latipes
{{Short description|Species of flowering plant}}
{{Use Australian English|date=July 2024}}
{{speciesbox
| name = Robust elbow orchid
| image = Arthrochilus latipes (4437242906).jpg
| image_caption = Arthrochilus latipes in Kakadu National Park
| genus = Arthrochilus
| species = latipes
| authority = D.L.Jones
}}
Arthrochilus latipes, commonly known as robust elbow orchid, is a flowering plant in the orchid family (Orchidaceae) and is endemic to the "Top End" of the Northern Territory in Australia. Each plant has from two to four ground-hugging leaves and between three and fifteen flowers during the wet season and the species often forms spreading colonies on sandstone escarpments. Like others in the genus, the flowers are pollinated by a species of thynnid wasp.
Description
Arthrochilus latipes is a terrestrial, perennial, deciduous, sympodial herb with an underground tuber which produces daughter tubers on the end of root-like stolons. There are two to four lance-shaped, ground-hugging, dull green leaves at the base of the plant, each leaf {{convert|25-70|mm|in|sigfig=1|abbr=on}} long and {{convert|8-26|mm|in|sigfig=1|abbr=on}} wide.{{cite journal|last1=Jones|first1=David L.|title="New taxa of Australian Orchidaceae"|journal=Australian Orchid Research|date=1991|volume=2|pages=8–9}}{{cite web |author1=D.L.Jones |author2=T.Hopley |author3=S.M.Duffy |author1-link=David L. Jones (botanist) |year=2010 |access-date=31 May 2021 |url=http://www.canbr.gov.au/cpbr/cd-keys/RFKOrchids/key/rfkorchids/Media/Html/Arthrochilus_latipes.htm |title=Factsheet - Arthrochilus latipes |website=Australian Tropical Rainforest Orchids |publisher=Centre for Australian National Biodiversity Research (CANBR), Australian Government}}
The inflorescence is a raceme, {{convert|10-30|cm|in|sigfig=1|abbr=on}} tall with three to about fifteen flowers, each {{convert|15-25|mm|in|sigfig=1|abbr=on}} long with and green with brownish glands on the labellum. The dorsal sepal curves downwards, is narrow egg-shaped to spoon-shaped, about {{convert|14|mm|in|sigfig=1|abbr=on}} long, {{convert|3-4|mm|in|sigfig=1|abbr=on}} wide and is wrapped around one-quarter of the column. The lateral sepals and petals are turned back towards the ovary, the sepals about {{convert|10x3.5|mm|in|sigfig=1|abbr=on}} and the petals about the same length but narrower. The labellum is about {{convert|7.5x1.5|mm|in|sigfig=1|abbr=on}} but wider at the base, greenish with a dark purple blotch at its base. The callus resembles a flightless female thynnid wasp and is covered with short, shiny, club-shaped, yellowish brown to brown structures called "calli". The tip of the callus is bulb-shaped and covered with shiny black glands. The column is shaped like a semi-circle, about {{convert|10|mm|in|sigfig=1|abbr=on}} long with its inner surface hairy. One pair of column wings are triangular and point forwards, while the other pair on the side of the column are erect and have a hooked summit. Flowering occurs from October to January and is followed by a dehiscent, oval-shaped capsule about {{convert|10|mm|in|sigfig=1|abbr=on}} long.
Taxonomy and naming
Arthrochilus latipes was first formally described in 1991 by David Jones and the description was published in Australian Orchid Research from a specimen collected in Radon Gorge in Kakadu National Park.{{cite web|title=Arthrochilus latipes|url= http://id.biodiversity.org.au/instance/apni/551528|publisher=APNI|accessdate=23 July 2016}} The specific epithet (latipes) is derived from the Latin words latus meaning "broad"{{cite book|last1=Brown|first1=Roland Wilbur|title=The Composition of Scientific Words|date=1956|publisher=Smithsonian Institution Press|location=Washington, D.C.}}{{rp|166}} and pes meaning "foot"{{rp|343}} referring to the broad base of the labellum of this orchid species.
Distribution and habitat
Robust elbow orchid is found in the Top End of the Northern Territory, east of Darwin, growing on rocky outcrops and sandstone escarpments, especially in the Kakadu and Litchfield National Parks.{{cite web|title=Arthrochilus latipes|url=http://eflora.nt.gov.au/factsheet?id=4058|publisher=Northern Territory Government: Flora NT|accessdate=23 July 2016}}
Ecology
As with other Arthrochilus orchids, robust elbow orchid is pollinated by males thynnid wasps of the genus Arthrothynnus although the species involved is not known. It also reproduces asexually by producing new tubers.{{cite web|title=Arthrochilus|url=https://www.anbg.gov.au/cpbr/cd-keys/orchidkey/html/genera/Arthrochilus.htm|publisher=Australian National Botanic Garden|accessdate=23 July 2016}}